#include <stdio.h>
#include <string.h>
#include <stdlib.h>

int main()
{
    char numStr[51];
    int twoN = 0, idx = 0, cnt = 0; // cnt计算位数,不算负号
    double twoDegree;
    fgets(numStr, 51, stdin);
    while (numStr[idx] != '\0' && numStr[idx] != '\n')
    {
        if (numStr[idx] != '-')
        {
            cnt++;
        }
        if (numStr[idx] == '2')
        {
            twoN++;
        }
        idx++;
    }
    if (numStr[idx] == '\n')
    {
        numStr[idx] = '\0';
    }
    twoDegree = (double)twoN / cnt;
    if (numStr[0] == '-')
    {
        twoDegree *= 1.5;
        if (atoi(&numStr[strlen(numStr) - 1]) % 2 == 0)
        {
            twoDegree *= 2;
        }
    }
    twoDegree *= 100;
    printf("%.2f%%", twoDegree);
    
    return 0;
}